The present invention relates to novel compounds, which have the properties of liquid crystals and are stable to u.v. radiation, together with process for their production and liquid crystal devices (LCDs) incorporating them.
The term “Liquid Crystals” is well known. It refers to compounds which, as a result of their molecular structure, will align themselves in a similar orientation, preferably at working temperatures, for example of from −40 to 200° C. Liquid crystal materials are well known for their use in electro-optical display devices, such as PDA, mobile phones laptop computer screens, watches and the like. The most commonly used type of liquid crystal material is that which shows a nematic liquid crystalline phase. Desirable characteristics in a nematic liquid crystal material include a high nematic to isotropic transition temperature, a low solid crystal to nematic transition temperature, and the absence of smectic (S) phases.
Other desirable characteristics include low viscosity, ease of manufacture, chemical and thermal stability. Nematic liquid crystal materials used in LCDs generally consist of a mixture of chemical compounds.
Conventional techniques of fluorinated liquid crystal are disclosed in the following patent documents 1 and 2. The present invention succeeded in producing liquid crystal material different from that disclosed in the documents.
Patent document 1: EP-B-418362
Patent document 2: EP-B-732330